A recent Searchmetrics performance study of 10 leading U.S. brands found that Amazon far outstripped its closest competitors in Google mobile search visibility.
The study took the top 10 retail sites in the National Retail Federation’s list of top 100 retailers and analyzed the search results of millions of Google search terms in order to formulate a mobile visibility score along with a desktop visibility score. Amazon lead the pack with an overwhelming rating of 11,145,359, outstripping its closest competitor – Walmart, with a score of 1,816,192 – by millions. Rounding out the top four were The Home Depot, with 881,538, and Target.com, which had a score of 771,839. 
Because mobile search is usually the first touch point to purchase, leaving final purchases to desktop, Searchmetrics also looked at visibility for desktop, though the rankings remained unchanged.
To calculate visibility scores, the company looks at the number of times a brand appears across a keyword set, the brand’s rankings within those search engine results pages (SERP), competitiveness of keywords, and the click through rates of those SERPs.